Observations on the nucleus of resting and germinating spores of Bacillus megaterium.

Information on nuclei in bacterial spores was both scanty and inconsistent until the Feulgen technique, in the hands of Stille (1937), Delaporte (1939), Schaede (1939) and others, revealed Feulgen positive matter in the shape of a granule or rodlet at the periphery of the majority of mature, resting spores of many well known Bacilus species, including Bacllus megaterium. A more detailed picture was obtained when hydrolysis with N/i HCl at 60 C, the initial step of the Feulgen procedure, was followed by staining with Giemsa solution, hematoxylin, or crystal violet in the place of the conventional S02fuchsin (Schiff reagent). Numerous concordant observations made with this useful, if less specific, technique have confirmed and extended the older findings of peripheral chromatinic bodies in resting, viable bacterial spores (Robinow, 1942, 1945, 1951; Klieneberger-Nobel, 1945; Flewett, 1948; Delaporte, 1950, Preuner, 1951; Bisset and Hale, 1951). In most of these investigations, e.g., those of Delaporte (1939, 1950) or Robinow (1942, 1945), the spores first had been fixed with osmium tetroxide vapor or by some other conventional procedure before they were hydrolyzed and stained. Later it was found that hydrolysis need not be carried out at the standard temperature of 60 C but is effective already at room temperature; that the result of hydrolysis is the same with living or variously fixed spores and that the peripheral nuclear element which becomes stainable during hydrolysis is visible clearly already in the unstained condition. In other words, the complex procedures used in the earlier work proved reducible to one single essential treatment-acid hydrolysis. With these facts well established by numerous experiments, it is surprising to find that DeLamater and Hunter (1952) and Hunter and DeLamater (1952), using a technique which